Commonly assigned U.S. Pat. No. 5,448,049 describes a bar code reader of the type utilizing an illumination source and a linear array of CCD elements extending transversely from one side wall of the film transport path. When suitably clocked out, each CCD element provides a signal dependent on the intensity of the illumination received. The output signals from the CCD array are processed to detect an edge of the filmstrip by the contrast in signal amplitude due to attenuation of the transmitted light intensity by the filmstrip substrate at the junction of the filmstrip with a gap separating the filmstrip edge and the side wall of the transport path. The bar code pattern is in a fixed position relative to the edge of the filmstrip and, therefore, once the edge of the filmstrip is identified, the (bar code segments can be readily located relative to the film edge for sampling and digitizing to discern the bar code pattern and resultant code value irrespective of any sideways motion ("wander") of the filmstrip through the reader. Location of the film edge and thus of the bar code pattern segments relies on the detection of the transition between light transmitted directly from the light source and light transmitted through the filmstrip.
This type of bar code location and reading apparatus, while effective, has a disadvantage that it is not readily adaptable to use in a compact film scanner as part of a film scanning gate in which both film image and marginal optical data is detected by a common CCD array. If unfiltered light outside the edge of the film is allowed to pass on to the CCD array, the unfiltered light introduces overall flare on the CCD in the image detection area and reduces the contrast of the image. Such unfiltered light can also create specular effects that can produce what is referred to as "hot spots" in the detected image. Additionally, filtered light, that is, light passing through the filmstrip, can bounce off the sides of the imaging channel housing which can produce ghost reflections in the detected image.
It is an object of the present invention, therefore, to provide a bar code image detection and reading method and apparatus utilizing a linear sensor array, such as a CCD, that does not rely on detection of the edge of the filmstrip on which the bar code pattern is imprinted.
It is also an object of the invention to provide a film scanning imaging channel that performs both image scanning and bar code reading through an imaging aperture using a common linear CCD array.